The invention relates generally to devices for supporting a joint in the limb of an animal, such as the joint between the tibia and the tarsus. The invention is attachable to desired bones of the animal via bone pins that penetrate the bone and extend through the animal flesh. Put another way, the joint support of the present invention is an external bone-joint fixator. The joint support has certain adjustable features, but once it is placed in an adjusted position, the joint support has a single degree of freedom about a hinge. When attached to pre-selected bones of an animal so that the hinge overlies a joint located between the bones, the joint support limits movement of that joint to the single degree of freedom of the support.
It is known to attach an external, mechanically hinged joint brace to a human limb, with the hinge overlying a joint in that limb. For example, U.S. Pat. No. 5,376,091 discloses several such braces. Another such conventional brace is known as the Richards-Illizarov System.
However, conventional joint braces have been constructed only for application to human joints. Such joint braces are ineffective for application to animals, at least in part because they are too complicated, and thus likely to be damaged or otherwise disturbed by the animal while wearing the brace. Conventional joint braces are also structurally inadequate for joints in animal limbs.
The present invention provides a joint support that effectively supports the joints of animals, and is particularly suited for use with domesticated animals such as dogs and cats. The invention generally includes a hinge, a radial support element attached to one side of the hinge, and a transverse support element attached to the other side of the hinge. The transverse element rotates relative to the radial element, with the transverse element rotating tangentially about the hinge. Tangential rotation means that the axial portion of the transverse element closest to the axis of rotation of the hinge defines substantially a circle as it rotates around the hinge, and the longitudinal axis of the transverse element is about tangent to the defined circle.
In the preferred embodiment, the hinge includes what is referred to as a radial block and a transverse block, with the radial block being that portion of the hinge that is attached to the radial support element, and the transverse block being that portion of the hinge that is attached to the transverse support element. The radial support element is fixed to the radial block, and the transverse support element extends through the transverse block to define an anterior portion and a posterior portion of the transverse element. In one embodiment of the present invention, the transverse element is releasably retained within the transverse block by a setscrew so that the proportion of the length of the anterior portion to the length of the posterior portion can be adjusted as necessary. Alternatively, the transverse element can be permanently affixed to the transverse block. In either embodiment, both the transverse and radial elements can be cut to any desired length.